(a) What is a balanced diet?

(b) (i) Name four classes of food other than proteins
(ii) Give one example of food substance for each class named

(c)(i) State three functions of proteins in humans.
(ii) Describe the appearance of a child with protein deficiency.

(d)(i) Name one organelle in a living cell that produces enzymes.
(ii) Mention two enzymes that act on proteins.